Abstract：
CONCLUSIONS: The investigation is the first report on genome-wide identification and characterization of NBLRR genes in pearl millet. We have shown the role of gene loss and purifying selection in the divergence of NBLRRs in Poaceae lineage and candidate CaNBLRR genes for resistance to Magnaporthe grisea infection. Plants have evolved multiple integral mechanisms to counteract the pathogens\' infection, among which plant immunity through NBLRR (nucleotide-binding site, leucine-rich repeat) genes is at the forefront. The genome-wide mining in pearl millet (Cenchrus americanus (L.) Morrone) revealed 146 CaNBLRRs. The variation in the branch length of NBLRRs showed the dynamic nature of NBLRRs in response to evolving pathogen races. The orthology of NBLRRs showed a predominance of many-to-one orthologs, indicating the divergence of NBLRRs in the pearl millet lineage mainly through gene loss events followed by gene gain through single-copy duplications. Further, the purifying selection (Ka/Ks < 1) shaped the expansion of NBLRRs within the lineage of pear millet and other members of Poaceae. Presence of cis-acting elements, viz. TCA element, G-box, MYB, SARE, ABRE and conserved motifs annotated with P-loop, kinase 2, RNBS-A, RNBS-D, GLPL, MHD, Rx-CC and LRR suggests their putative role in disease resistance and stress regulation. The qRT-PCR analysis in pearl millet lines showing contrasting responses to Magnaporthe grisea infection identified CaNBLRR20, CaNBLRR33, CaNBLRR46 CaNBLRR51, CaNBLRR78 and CaNBLRR146 as putative candidates. Molecular docking showed the involvement of three and two amino acid residues of LRR domains forming hydrogen bonds (histidine, arginine and threonine) and salt bridges (arginine and lysine) with effectors. Whereas 14 and 20 amino acid residues of CaNBLRR78 and CaNBLRR20 showed hydrophobic interactions with 11 and 9 amino acid residues of effectors, Mg.00g064570.m01 and Mg.00g006570.m01, respectively. The present investigation gives a comprehensive overview of CaNBLRRs and paves the foundation for their utility in pearl millet resistance breeding through understanding of host-pathogen interactions.
摘要：
结论：这项研究是关于珍珠小米中NBLRR基因的全基因组鉴定和表征的第一份报告。我们已经证明了基因丢失和纯化选择在禾本科谱系中NBLRR和候选CaNBLRR基因对稻瘟病菌感染的抗性中的作用。植物已经进化出多种完整的机制来抵抗病原体的感染，其中植物免疫通过NBLRR(核苷酸结合位点，富含亮氨酸的重复)基因走在前列。珍珠小米的全基因组采矿（Cenchrusamericanus（L.)Morrone)揭示了146个CaNBLRR。NBLRR分支长度的变化显示了NBLRR响应于不断发展的病原体种族的动态性质。NBLRR的正交研究显示了多对一直系同源物的优势，表明珍珠谷子谱系中NBLRR的分歧主要是通过基因丢失事件，然后通过单拷贝复制获得基因。Further,纯化选择（Ka/Ks<1）促进了梨小米和禾本科其他成员谱系内NBLRR的扩展。存在顺式作用元素，viz.TCA元件,G-box,MYB,SARE,ABRE和用P环注释的保守基序，激酶2，RNBS-A，RNBS-D,GLPL,MHD,Rx-CC和LRR表明它们在抗病和应激调节中的推定作用。在珍珠小米品系中的qRT-PCR分析显示出对稻瘟病菌感染的相反反应，将CaNBLRRR20，CaNBLRR33，CaNBLRR46CaNBLRR51，CaNBLRR78和CaNBLRR146确定为推定的候选物。分子对接显示LRR结构域的三个和两个氨基酸残基参与形成氢键（组氨酸，精氨酸和苏氨酸）和盐桥（精氨酸和赖氨酸）与效应物。而CaNBLRR78和CaNBLRR20的14和20个氨基酸残基显示与效应子的11和9个氨基酸残基的疏水相互作用，Mg.00g064570。M01和Mg.00g006570。分别为m01。本研究全面概述了CaNBLRR，并通过了解宿主-病原体相互作用为其在珍珠小米抗性育种中的应用奠定了基础。
